Process for transferring files from one computing device to another

ABSTRACT

A handheld computing device is used to copy files from the screen of a fixed computer. The display of the handheld device is linked to that of the underlying computer and file and directory icons together with their underlying files are copied to the handheld device. Files from the handheld device can also be transferred to the fixed computer. When a user is running a program on the fixed computer, he may capture the state of that computer and transfer everything needed to permit execution of that program to continue uninterrupted on the handheld device. Thus files and executing programs may be lifted from the fixed computer and used on the handheld device.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to computer systems, and more particularly,to the transfer of files between computer systems not physicallynetworked together.

[0003] 2. Description of Related Art

[0004] When transferring files between computer systems, it is common toutilize an intermediary diskette. A diskette is loaded into a disk driveof one computer system, the file to be transferred is copied to thatdiskette, and then the diskette is transported physically to thecomputer system to which the transfer is to occur and placed in a diskdrive of that system. The file is then copied from the diskette to thetarget computer system.

[0005] Computers which are networked together, may transfer files eitherdirectly, such as when using a file transfer protocol (FTP), orindirectly via the intermediary of a server. In some systems, all filesare stored on a central server and all terminals have access to them,subject to the appropriate security clearance.

[0006] The Problems

[0007] The transfer of files using a diskette is slow and cumbersome.Transfers must occur twice, first from the source computer to thediskette and then from the diskette to the target computer. Diskettesare limited as to their capacity and often, a file must be broken up andstored on separate diskettes in order to be effectively transferred. Theuser interfaces utilized to activate a copy command are often notconvenient making the transfer difficult. Selecting files, folders andcontainers from crowded iconic desk tops also creates difficulties. Inthe network environment, users are often less familiar with theinvocation of network commands utilized to transfer files then they arewith the operation of their own computer.

SUMMARY OF THE INVENTION

[0008] The present invention provides apparatus, systems, processes andcomputer program products which provide new techniques for transferringfiles between computers. In typical operation, the user will have alarge, fixed computer and a relatively small, handheld flat screencomputer, reader or other dedicated flat screen computing device. Intypical operation, a user will have an active screen open on the largecomputer's display. By placing the small flat screen device over theimage of a file, the screens of the two computing devices are linked sothat the small computer's display “bleeds through” and displays theportion of the large device display being covered on the small devicedisplay. This is constantly updated so that by moving the small handhelddevice over the surface of the large computer's display, differentportions of the screen can be displayed on the small computer's display.

[0009] In addition to linking of screens, files can be transferred fromthe fixed device to the handheld device by selecting a transfer mode andby placing an indicator, such as crosshairs on an icon of a file fromthe fixed device. A copy command then causes the file from the fixeddevice to be transferred to the handheld device using a communicationslink, such as an infrared or radio link. The position of the handhelddevice relative to the fixed computing device is determined using anultrasound, an infrared or a Polhemus-type six degrees of freedomlocator.

[0010] In another mode, the state of an operating program together withall needed files can be transferred to the handheld device over thecommunications link and execution of the program can continueuninterrupted on the handheld device. Alternatively, the handheld devicecan be slaved to the fixed device and operated remotely.

[0011] The file transfer mechanisms of the invention are particularlyuseful because they implement an analogy to picking up a physical fileand moving it to a different computer and putting it down. That is anatural kind of action that is comfortable to most users. It overcomesthe problems of the prior art in ways that are convenient to a user.

[0012] The invention relates to computer apparatus for linking with aportable computer for the transfer of information, including a bus, acentral processing unit connect to and controlling the bus, a wirelesstransceiver for sending information to and receiving information fromthe portable computer, and a position detector, connected to the bus,for determining the location and orientation of the portable computerwith respect to the computer apparatus. The position detector may be aphotocell or a Polhemus receiver. The wireless transceiver is aninfrared transceiver. A video buffer provides information to a display.The video buffer provides display information to the wirelesstransceiver based on the location and orientation of the portablecomputer.

[0013] The invention relates to a portable computer for linking with anon-portable computer for the transfer of information, including awireless transceiver for receiving information from the non-portablecomputer, and two video buffers, one of which provides information fromthe portable computer to a display, and the other of which providesinformation from the non-portable computer over the wireless transceivertwo the display.

[0014] The invention also relates to a method of linking the displayscreens of a first and a second computer, to display the sameinformation, by determining the position of the second computer relativeto the first computer, and transferring display information from thefirst computer to the second computer for display on the display screenof the second computer when the position of the display information onthe display screen of the first computer lies directly underneath alocation on the display screen of the second computer.

[0015] The invention is also directed to a method of copying one or morefiles from a first computer to a second computer, by linking the screensof the first computer and the second computer over a wirelesstransceiver to display the same information, selecting the one or morefiles for copying, and transmitting the one or more files from the firstcomputer to the second computer over the wireless transceiver.

[0016] The invention is also directed to a method of capturing a programrunning on a first computer to permit it to run on a second computer, bycopying all open files from the first computer to the second computer,copying memory space from the first computer to the second computer,linking the screens of the first computer to the second computer,copying registers and program counters from the first computer to thesecond computer, and beginning executing the program on the secondcomputer.

[0017] The invention is also directed to a method of slaving a firstcomputer to a second computer, by redirecting keyboard input so that itis received from the second computer over a wireless communicationslink, redirecting mouse input so that it is received from the secondcomputer over the wireless communications link, and redirecting displayoutput from the second computer over the wireless communications link.

[0018] The invention is also directed to a method of copying one or morefiles from a portable computer to a fixed computer, by placing the fixedcomputer into a receive mode, sending a name of a file or directory tobe used in storing the one or more files over a wireless link from theportable computer to the fixed computer, opening a file using the namein write mode, copying the contents of the one or more files from theportable computer to the fixed computer, and closing the file ordirectory.

[0019] The invention is also directed to a method of selecting files bylinking the screens of the first computer and the second computer over awireless transceiver to display the same information, and sendingcommands from the second computer to the first computer over a wirelesslink to emulate mouse commands originating at the first computer.

[0020] The invention is also directed to a method of freezing an imageon a display screen of a computer, by linking the screens of a firstcomputer and the second computer over a wireless transceiver to displaythe same information, determining the position of the second computerrelative to the first computer, and transferring display informationfrom the first computer to the second computer for display on thedisplay screen of the second computer (1) when the position of thedisplay information on the display screen of the first computer liesdirectly underneath a location on the display screen of the secondcomputer and the distance separating the display screen of the firstcomputer and the display screen of the second computer is less than afixed amount, and (2) otherwise, freezing the information on the displayscreen of the second computer.

[0021] The invention is also directed to a system for linking with aportable computer for the transfer of information, including a network,and a plurality of fixed computers connected to the network, at leastone of which has a wireless transceiver for sending information to andreceiving information from a nearby portable computer.

[0022] The invention is also directed to computer program products forcarrying out the techniques of the invention.

[0023] Still other objects and advantages of the present invention willbecome readily apparent to those skilled in the art from the followingdetailed description, wherein only the preferred embodiment of theinvention is shown and described, simply by way of illustration of thebest mode contemplated of carrying out the invention. As will berealized, the invention is capable of other and different embodiments,and its several details are capable of modifications in various obviousrespects, all without departing from the invention. Accordingly, thedrawing and description are to be regarded as illustrative in nature,and not as restrictive.

BRIEF DESCRIPTION OF DRAWINGS

[0024] The objects, features and advantages of the system of the presentinvention will be apparent from the following description in which:

[0025]FIG. 1A illustrates a fixed computer of a type suitable forcarrying out the invention.

[0026]FIG. 1B is a block diagram of the computer of FIG. 1A.

[0027]FIG. 1C illustrates an exemplary memory medium containing one ormore programs useable with the computer of FIG. 1A.

[0028]FIG. 2 illustrates a portable computer suitable for use with thefixed computer of FIG. 1 in carrying out the invention.

[0029]FIG. 3 is an illustration of how the portable computing device ofFIG. 2 is positioned with respect to the fixed computing device of FIG.3 for file transfer.

[0030]FIG. 4 is a block diagram of circuitry for sending screeninformation from the fixed device to the portable device for display.

[0031]FIG. 5 is a block diagram of circuitry for receiving anddisplaying screen information sent from the fixed device.

[0032]FIG. 6 is a partial block diagram of the bus structure of FIG. 1Butilized to explain transfer of files between a fixed and a portabledevice.

[0033]FIG. 7 is a flowchart of a process for transferring files from afixed device to a portable device.

[0034]FIG. 8 is a flowchart of a process for “capturing” or transferringa running application from a fixed device to a portable device whereexecution may continue.

[0035]FIG. 9 is a flowchart of a process for running the fixed computerin a mode in which it is slaved to the portable device.

[0036]FIG. 10 is a flowchart of a process for sending a file ordirectory from a portable device to a fixed device.

[0037]FIG. 11 illustrates a high resolution source of image informationconverted down to two different resolutions.

[0038]FIG. 12 is a block diagram of fixed and portable display apparatusfor controlling addressing.

[0039]FIG. 13 shows an alternative for locating the portable displaylocation on the fixed display.

[0040]FIG. 14 is a flowchart of an exemplary process for freezing theimage on the screen of the small device display when it is lifted fromthe display of the large screen.

NOTATIONS AND NOMENCLATURE

[0041] The detailed descriptions which follow may be presented in termsof program procedures executed on a computer or network of computers.These procedural descriptions and representations are the means used bythose skilled in the art to most effectively convey the substance oftheir work to others skilled in the art.

[0042] A procedure is here, and generally, conceived to be aself-consistent sequence of steps leading to a desired result. Thesesteps are those requiring physical manipulations of physical quantities.Usually, though not necessarily, these quantities take the form ofelectrical or magnetic signals capable of being stored, transferred,combined, compared, and otherwise manipulated. It proves convenient attimes, principally for reasons of common usage, to refer to thesesignals as bits, values, elements, symbols, characters, terms, numbers,or the like. It should be noted, however, that all of these and similarterms are to be associated with the appropriate physical quantities andare merely convenient labels applied to these quantities.

[0043] Further, the manipulations performed are often referred to interms, such as adding or comparing, which are commonly associated withmental operations performed by a human operator. No such capability of ahuman operator is necessary, or desirable in most cases, in any of theoperations described herein which form part of the present invention;the operations are machine operations. Useful machines for performingthe operation of the present invention include general purpose digitalcomputers or similar devices.

[0044] The present invention also relates to apparatus for performingthese operations. This apparatus may be specially constructed for therequired purpose or it may comprise a general purpose computer asselectively activated or reconfigured by a computer program stored inthe computer. The procedures presented herein are not inherently relatedto a particular computer or other apparatus. Various general purposemachines may be used with programs written in accordance with theteachings herein, or it may prove more convenient to construct morespecialized apparatus to perform the required method steps. The requiredstructure for a variety of these machines will appear from thedescription given.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0045]FIG. 1A illustrates a fixed computer of a type suitable forcarrying out the invention. Viewed externally in FIG. 1A, a computersystem has a central processing unit 100 having disk drives 110A and110B. Disk drive indications 110A and 110B are merely symbolic of anumber of disk drives which might be accommodated by the computersystem. Typically, these would include a floppy disk drive such as 110A,a hard disk drive (not shown externally) and a CD ROM drive indicated byslot 110B. The number and type of drives varies, typically, withdifferent computer configurations. The computer has the display 120 uponwhich information is displayed. A keyboard 130 and a mouse 140 aretypically also available as input devices. Preferably, the computerillustrated in FIG. 1A is a SPARC workstation from Sun Microsystems,Inc. A three dimensional position detector for receiving positioninformation from another device is shown at 180.

[0046]FIG. 1B illustrates a block diagram of the internal hardware ofthe computer of FIG. 1A. A bus 150 serves as the main informationhighway interconnecting the other components of the computer. CPU 155 isthe central processing unit of the system, performing calculations andlogic operations required to execute programs. Read only memory (160)and random access memory (165) constitute the main memory of thecomputer. Disk controller 170 interfaces one or more disk drives to thesystem bus 150. These disk drives may be floppy disk drives, such as173, internal or external hard drives, such as 172, or CD ROM or DVD(Digital Video Disks) drives such as 171. An I/B interface 145 connectskeyboard 130 and mouse 140 to the bus. A display interface 175interfaces a display 120 and permits information from the bus to beviewed on the display. Communications with external devices can occurover communications port 185. Transceiver 125, connected to the bus overinterface 124 is used to communicate with another computing device.Preferably, this is an infrared (IR) transceiver. Three dimensionalposition detector 180 is connected to the bus over interface 179.Position or location detector 180 may be an ultrasound, infrared (IR) orPolhemus-type six degree of freedom locator. Polhemus devices aremanufactured by Polhemus, Incorporated of Colchester, Vt.

[0047]FIG. 1C illustrates an exemplary memory medium which can be usedwith drives such as 173 in FIG. 1B or 110A in FIG. 1A. Typically, memorymedia such as a floppy disk, or a CD ROM, or a Digital Video Disk willcontain the program and data information for controlling the computer toenable the computer to perform its functions in accordance with theinvention.

[0048]FIG. 2 illustrates a portable computer suitable for use with thefixed computer of FIG. 1 for carrying out the invention. The handheldcomputing device shown in FIG. 2 includes a display screen 220, akeyboard or series of keys 230 and a track wall mouse 240 all to assistin carrying out the usual functionality of a computer. In addition, thehandheld device includes a position sender 210 for sending the locationand orientation of the device vis a vis a receiver located on a fixedcomputer to be used for, inter alia, linking the displays to the twodevices so that the information shown on the display of the device ofFIG. 2 parallels the information shown on the portion of the display ofthe device of FIG. 1A which lies directly beneath it. In addition, thehandheld device of FIG. 2 includes an exemplary infrared transceiver 220for communicating information between the computer shown in FIG. 2 andthat shown in FIG. 1A.

[0049] The block diagram as shown in FIG. 1B also depicts the internalconstruction of the handheld device shown in FIG. 2.

[0050]FIG. 3 is an illustration of how the portable computing device ofFIG. 2 is positioned with respect to the fixed computing device of FIG.3 for file transfer. As shown in FIG. 3, handheld computing device 300is placed on the display screen 330 of a fixed computing device.Location sender 310 on the handheld device sends location information tolocation receiver 320 on the fixed device. Display screen 330 on thefixed device and display screen 340 on the portable handheld device aredefined with a coordinate system which has an origin, for purposes ofthis example, in the lower left hand corner. The location of the originof the coordinate system for display screen 340 on the portable device,O_(P), is displaced from the origin of the location sender 310 mountedon the same device by a fixed amount. Thus, although location sender 310specifies the location of itself with respect to location receiver 320,the location of the origin of the display for the portable device isknown because it is a fixed offset from the location of the locationsender. Similarly, the location of the origin of the fixed display,O_(F), is known because it represents a fixed offset with respect to theposition of location receiver 320. Thus, the position of the handhelddisplay screen is known with respect to the coordinate system utilizedfor the large display screen. For example, as shown in FIG. 3, theorigin of the handheld display screen, O_(P), is positioned atcoordinates X1, Y1 of the fixed screen. The display screen of thehandheld device, 340, has an X extent equal to X_(P) and a Y extentequal to Y_(P). Thus, the addresses from the display space of the largescreen 330, which corresponds to the address space for the small screen340 of the handheld device are known.

[0051] For ease of explanation of the operation of the invention, itwill be assumed for purposes of the example that the resolution of thetwo display screens are identical, that the CPU's are identical and thatthe memory spaces of the two devices are identical. These assumptionsare not necessary but it simplifies the explanation of the invention.

[0052]FIG. 4 is a block diagram of circuitry for sending screeninformation from the fixed device to the portable device for display. Asshown in FIG. 4, the normal source of image information 410 for fixeddevice display 420 is read and written to appropriate locations in adual port video buffer 415 under control of write control 430. Thedisplay 420 is periodically updated with information read from the dualport video buffer 415 under control of read control 440. Thus, the dualport video buffer may be updated concurrently with new image informationfrom source 410 while the display is being updated with the contents ofthe dual port video buffer via read control 440. Read control 440 haslocation information for the position of the handheld device displayscreen vis a vis the main display screen as illustrated in FIG. 3.Therefore, read control 440 knows which portion of the image informationshown on display 420 underlies the display screen of the handhelddevice. Read control 440 opens the transfer gate 450 and allows theportion of the information displayed on display 420 to also be sent overinfrared transceiver 425 to the handheld device. In this way, theinformation underlying the display of the portable device is displayedon the portable device is sent to the portable device and displayed onthe portable device. During times when information is not beingtransferred across transfer gate 450, sync pulses 450 may be sent toensure that the clocks in read and write controls of the portablehandheld device are in synchronization with those of the fixed device.

[0053]FIG. 5 is a block diagram of circuitry for receiving anddisplaying screen information sent from the fixed device. Imageinformation source 510 read control 540, write control 530 dual portvideo buffer 515 and display 520 function when switch 580 is in theposition shown to act as a normal display. The operation of that normaldisplay corresponds to that described in conjunction with FIG. 4.However, when the screens of the portable and fixed displays are to belinked so as to display the same information, switch 580 moves to thealternate position. In the alternate position, image informationreceived from the fixed device over IR transceiver 525 is written intodual port portable buffer 515′ under control of clock recovery circuit570 and sync pulses 565. The information for the display 520, in thismode, is then read from the auxiliary dual port video buffer 515′ anddisplayed on display 520. Thus, display 520 can obtain its informationinternally from image information source 510 or may obtain it externallyfrom the fixed device over IR transceiver 525. In this way, the screensof the two devices may be linked so as to display the same information.

[0054]FIG. 6 is a partial block diagram of the bus structure of FIG. 1Bused to explain transfer of files between a fixed and a portable device.As shown in FIG. 6 a mouse 640 is connected to bus 650 via a mousecontroller or interface 645. Similarly, a transceiver 625 is connectedthrough its interface 624 to the bus 650. The CPU 655 manages theinteraction of these devices on the bus. Each device on the bus istypically handled by a device handler which is a program which typicallyterminates and stays resident to be invoked as needed. To facilitate thetransfer of files, in this exemplary implementation, interactions that amouse 640 would normally have through its controller with the devicehandler for the mouse are emulated and sent over IR transceiver 625 tothe bus 650. Thus, mouse functions such as those utilized in copyingfiles can be emulated by the portable handheld device and sent to thebus of the fixed device 650 to invoke actions on the part of the CPU 655as if the commands were generated by mouse 640.

[0055]FIG. 7 is a flowchart of a process for transferring files from afixed device to a portable device. To initiate file transfer, a transfermode is selected at the handheld device (700). The screens of thehandheld and the fixed device are linked (710) and crosshairs aredisplayed on the center of the screen of the handheld device (720). Theuser places the crosshairs over the icon of a file or directory to becopied (730), and since both screens identically are displaying the sameinformation by virtue of the linkage established at 710, the same iconsare being viewed. The address of the center of the crosshairs istranslated to a display address of a display location on the fixedcomputer display screen (740) and mouse commands are emulated to placethe cursor on the fixed display screen over the file icon selected onthe handheld display screen (750). A file name or list of file names fora directory associated with the selected icon are obtained from a filemanagement system on the fixed computer and sent to the portable unit(760). The file or list of files are copied to a device number for theIR transceiver (770) and the files are sent to the portable device wherethey are received and stored under the name or names sent (780).

[0056]FIG. 8 is a flowchart of a process for “capturing” or transferringa running application from a fixed device to a portable device orexecution may continue. Capturing an operating application involvesessentially doing everything required to place a portable device into.the same state with respect to the software as if the portable devicewere the fixed device. In many respects, the process is like returning acomputer to a process after a context switch in a multi-taskingenvironment, such as that which occurs in UNIX. At a high level, oneneeds to identify all relevant files necessary to run the application,to make sure that the memory space is set up with all information neededto run the program and to ensure that the CPU registers, programcounters and the like are set up to coincide with the state at which theprogram left execution. In addition, the screens need to be linked sothat both screens display the same information. This all is reflected inthe process shown in FIG. 8. At step 800, a list of open files areobtained from the file manager system of the fixed device (800). Thehighest level directory encompassing all open files (810) is determinedand copied together with all subordinate directories to the portabledevice (820). The memory space is copied into the portable device (830).The operating state of the CPU is reflected in the registers, programcounters and other state defining elements are transferred to theportable device (840) to set the CPU into the same state as that of thefixed device and information from one screen is displayed on the otherscreen (850). This time, the program is ready to resume execution whereit left off.

[0057]FIG. 9 is a flowchart of a process for running the fixed computerin a mode in which it is slaved to the portable device. Essentially theprocess is one of redirecting all inputs and outputs to the portabledevice. As shown at 900, the keyboard input is directed to be receivedfrom the portable device over the IR link (900). The mouse input isredirected to be received from the portable device (910) and displayoutput is redirected to the portable device (920). If the displays areof identical resolution, the amount of information displayed on theportable device screen will be less than a full screen of the fixeddevice, because it is smaller. However, if resolution is higher, a fullscreen's worth of display may be accommodated. Resolution and resolutionconversion is discussed more hereinafter.

[0058]FIG. 10 is a flowchart of a process for sending a file ordirectory from a portable device to a fixed device. The IR link betweenthe two computing devices is opened (1000) and the fixed computer isplaced into a receive mode (1010). The portable device sends the name ofthe file or directory to be transferred to the fixed device (1020) wherea file or directory with that same name on the fixed computer is createdand opened in a write mode (1030). The file or directory is then copiedto the IR transceiver link and sent to the fixed computer (1040). Oncethe end of file has been reached (1050), the file or directory is closedon the fixed computer (1060) and the process ends. If end of file hasnot been reached, the transfer continues.

[0059]FIG. 11 illustrates a high resolution source of image informationconverted down to two different resolutions. In the example shown inFIG. 11, image storage 1100 contains all information needed to store a8″×12″ image at 400 dpi (dots per inch or pixels per inch). Such imagestorage would require approximately 15.36 million pixels. By using a400:1 pixel averaging technique or other resolution conversiontechniques, the image represented in image storage 1100 can be displayedat 100 dpi spread over the same area using only 960,000 pixels (1120).The same image stored in image storage 1100 can be converted down at a40:1 conversion ratio to represent a much higher resolution display forthe viewport display. At 200 dpi, the image stored in image storage 1100can be represented with only 3.84 million pixels (1140) . Thus, the highresolution information stored in image storage 1100 can be displayed ona low or resolution device, on fixed device display at 100 dpi and thehandheld display can display the same image at 200 DPI, thus coveringmore of the fixed device screen area on a smaller display.

[0060]FIG. 12 is a block diagram of apparatus for selecting sources ofimage information and for controlling addressing.

[0061] The image shown on display 1200 is derived from video buffer 1205which contains a subset of information stored in image section buffer1210 as described more hereinafter. Memory or mass storage 1225 containsimage information to be displayed. As discussed in conjunction with FIG.11, this can be a very high resolution image stored. The high resolutionimage information is converted in display resolution transform 1215 to aresolution appropriate for the display 1200. A selector 1220 is utilizedto select sources of information for display on viewport display 1200.Fixed display 1235 is a low resolution device and the image displayed isderived from the high resolution version stored in memory 1225 using lowresolution transform 1245. Note that the clock speed is required todeliver all pixels of a high resolution storage such as 1225 and thoserequired to deliver a lower resolution version of the same image differ.Thus, if clock address generator 1250 is driving the readout, for alldevices, it must be divided down in order to control the readout of thelower resolution displays. This division down is illustrated in 1255 inFIG. 12. A similar activity occurs in 1260 with respect to the highresolution display, however, only a portion of the overall informationavailable is needed for video buffer 1205. The location of the handhelddisplay can be derived from either a Polhemus device, a photocelldetection of a scanning location from the fixed display device.

[0062]FIG. 13 shows an alternative for locating the handheld displaywhen a scanning fixed display device is used. A handheld display 1300 ispositioned over a fixed display 1310. A photocell 1320 attached to thebottom of the viewport display 1300 detects when a light beam from thescanning display crosses the photocell. At that instant, the addressdriving the scanning display is captured to show the position at whichthe viewport display is located vis a vis the scanning driver. The exactaddress and location of the information displayed on the underlyingfixed display can be determined and utilized to determine theinformation to be provided on the screen of handheld display 1300.Clearly more than one photocell 1320 can be utilized to determine theorientation of the device vis a vis the backlit screen 1310.

[0063]FIG. 14 is a flowchart of an exemplary process for freezing theimage on the handheld display when it is lifted off the table. Using thedisplay location device, one determines whether the display has beenlifted off the table by an amount H which is greater than a threshold H1(1400). If it has been, the image displayed on the screen of the displayis frozen regardless of its translation with respect to the surface offixed display (1410). As long as the viewport display is located off thetable by an amount in excess of H1 (1420-Y), the image will remainfrozen. However, once it is placed back on the table, the normallocation information will be received and the image will achieve theproper content for the location at which it is replaced (1430).

[0064] In this disclosure, there is shown and described only thepreferred embodiment of the invention, but, as aforementioned, it is tobe understood that the invention is capable of use in various othercombinations and environments and is capable of changes or modificationswithin the scope of the inventive concept as expressed herein.

What is claimed is:
 1. Computer apparatus for linking with a portablecomputer for the transfer of information, comprising: a. a bus; b. acentral processing unit connect to and controlling said bus; c. awireless transceiver for sending information to and receivinginformation from said portable computer; and d. a position detector,connected to said bus, for determining the location and orientation ofsaid portable computer with respect to said computer apparatus. 2.Computer apparatus of claim 1 in which said position detector comprisesa photocell.
 3. Computer apparatus of claim 1 in which said positiondetector comprises a Polhemus receiver.
 4. Computer apparatus of claim 1in which said wireless transceiver is an infrared transceiver. 5.Computer apparatus of claim 1 further comprising a display and a videobuffer for providing information to said display.
 6. Computer apparatusof claim 5 in which said video buffer provides display information tosaid wireless transceiver based on the location and orientation of saidportable computer.
 7. A portable computer for linking with anon-portable computer for the transfer of information, comprising: a. awireless transceiver for receiving information from said non-portablecomputer; and b. two video buffers, one of which provides informationfrom said portable computer to a display; and the other of whichprovides information from said non-portable computer over said wirelesstransceiver two said display.
 8. A method of linking the display screensof a first and a second computer, to display the same information,comprising the steps of: a. providing an element for performing a stepof determining the position of said second computer relative to thefirst computer; and b. providing an element for performing a step oftransferring display information from said first computer to said secondcomputer for display on the display screen of said second computer whenthe position of said display information on the display screen of saidfirst computer lies directly underneath a location on the display screenof said second computer.
 9. A method of copying one or more files from afirst computer to a second computer, comprising the steps of: a.providing an element for performing a step of linking the screens ofsaid first computer and said second computer over a wireless transceiverto display the same information; b. providing an element for performinga step of selecting said one or more files for copying; and c. providingan element for performing a step of transmitting said one or more filesfrom said first computer to said second computer over said wirelesstransceiver.
 10. A method of capturing a program running on a firstcomputer to permit it to run on a second computer, comprising the stepsof: a. providing an element for performing a step of copying all openfiles from said first computer to said second computer; b. providing anelement for performing a step of copying memory space from said firstcomputer to said second computer; c. providing an element for performinga step of linking the screens of said first computer to said secondcomputer; d. providing an element for performing a step of copyingregisters and program counters from said first is computer to saidsecond computer; and e. providing an element for performing a step ofbeginning executing said program on said second computer.
 11. A methodof slaving a first computer to a second computer, comprising the stepsof: a. providing an element for performing a step of redirectingkeyboard input so that it is received from said second computer over awireless communications link; b. providing an element for performing astep of redirecting mouse input so that it is received from said secondcomputer over said wireless communications link; and c. providing anelement for performing a step of redirecting display output from saidsecond computer over said wireless communications link.
 12. A method ofcopying one or more files from a portable computer to a fixed computer,comprising the steps of: a. providing an element for performing a stepof placing said fixed computer into a receive mode; b. providing anelement for performing a step of sending a name of a file or directoryto be used in storing said one or more files over a wireless link fromsaid portable computer to said fixed computer; c. providing an elementfor performing a step of opening a file using said name in write mode;d. providing an element for performing a step of copying the contents ofsaid one or more files from the portable computer to said fixedcomputer; and e. providing an element for performing a step of closingthe file or directory.
 13. A method of selecting files comprising thesteps of: a. providing an element for performing a step of linking thescreens of said first computer and said second computer over a wirelesstransceiver to display the same information; and b. providing an elementfor performing a step of sending commands from said second computer tosaid first computer over a wireless link to emulate mouse commandsoriginating at said first computer.
 14. A method of freezing an image ona display screen of a computer, comprising the steps of: a. providing anelement for performing a step of linking the screens of a first computerand said second computer over a wireless transceiver to display the sameinformation; b. providing an element for performing a step ofdetermining the position of said second computer relative to the firstcomputer; and c. providing an element for performing a step oftransferring display information from said first computer to said secondcomputer for display on the display screen of said second computer (1)when the position of said display information on the display screen ofsaid first computer lies directly underneath a location on the displayscreen of said second computer and the distance separating said displayscreen of said first computer and the display screen of said secondcomputer is less than a fixed amount; and (2) otherwise, freezing theinformation on said display screen of said second computer.
 15. A systemfor linking with a portable computer for the transfer of information,comprising: a. a network; and b. a plurality of fixed computersconnected to said network, at least one of which has a wirelesstransceiver for sending information to and receiving information from anearby portable computer.
 16. A computer program product comprising: a.a memory medium; and b. a computer program stored on said medium, saidprogram comprising instructions for determining the position of a secondcomputer relative to a first computer; and for transferring displayinformation from said first computer to said second computer for displayon the display screen of said second computer when the position of saiddisplay information on the display screen of said first computer liesdirectly underneath a location on the display screen of said secondcomputer.
 17. A computer program product comprising: a. a memory medium;and b. a computer program stored on said medium, said program comprisinginstructions for linking the screens of a first computer and a secondcomputer over a wireless transceiver to display the same information,selecting said one or more files for copying; and transmitting said oneor more files from said first computer to said second computer over saidwireless transceiver.
 18. A computer program product comprising: a. amemory medium; and b. a computer program stored on said medium, saidprogram comprising instructions for copying all open files from saidfirst computer to said second computer; copying memory space from saidfirst computer to said second computer; linking the screens of saidfirst computer to said second computer; copying registers and programcounters from said first computer to said second computer; and beginningexecuting said program on said second computer.
 19. A computer programproduct comprising: a. a memory medium; and b. a computer program storedon said medium, said program comprising instructions for redirectingkeyboard input so that it is received from said second computer over awireless communications link; redirecting mouse input so that it isreceived from said second computer over said wireless communicationslink; and redirecting display output from said second computer over saidwireless communications link.
 20. A computer program product comprising:a. a memory medium; and b. a computer program stored on said medium,said program comprising instructions for linking the screens of saidfirst computer and said second computer over a wireless transceiver todisplay the same information; and sending commands from said secondcomputer to said first computer over a wireless link to emulate mousecommands originating at said first computer.
 21. A computer programproduct comprising: a. a memory medium; and b. a computer program storedon said medium, said program comprising instructions for linking thescreens of a first computer and said second computer over a wirelesstransceiver to display the same information; determining the position ofsaid second computer relative to the first computer; and transferringdisplay information from said first computer to said second computer fordisplay on the display screen of said second computer (1) when theposition of said display information on the display screen of said firstcomputer lies directly underneath a location on the display screen ofsaid second computer and the distance separating said display screen ofsaid first computer and the display screen of said second computer isless than a fixed amount; and (2) otherwise, freezing the information onsaid display screen of said second computer.